Simplified dual tank with sniper EFI

[Frankenchevy]

just thought I’d put this sketch out there for scrutiny before I begin bending hard pipe. The drawing is exaggerated to more clearly show the connections rather than actual location of routing.

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The driver side tank will be my primary use tank. It has an 80psi in-tank pump for supplying the Holley efi system. The passenger tank is for camping and longer trips. It will feed the primary tank with a 12v transfer pump. This is the part in question.

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In the drawing you will notice this: passenger tank supply feeding 12v transfer pump > into filter w/return(back to return on passenger sending unit) > into one way check valve > into ‘Y’ tube fitting then onto return of driver side sending unit.

The return from the Holley efi goes through a one way check valve, into the ‘Y’ fitting and back to return of driver side sending unit.

Any experienced guys see a problem with the one way check valve idea?

TIA

 

[theblindchicken]

Just spitballing here (no experience with efi or fuel systems).


Only issue I would see with combining is that if the pressure from the EFI return is greater than the 12v transfer pump, you may have issues with it filling the other tank. But if the pump is too high of pressure compared to the return, then the check valve for the EFI return wouldn't be able to operate.

Gotta have a high into low pressure for the check valve to operate. Can't do high pressure into higher.

 

[Frankenchevy]

Just spitballing here (no experience with efi or fuel systems).


Only issue I would see with combining is that if the pressure from the EFI return is greater than the 12v transfer pump, you may have issues with it filling the other tank. But if the pump is too high of pressure compared to the return, then the check valve for the EFI return wouldn't be able to operate.

Gotta have a high into low pressure for the check valve to operate. Can't do high pressure into higher.

Good point...

I guess I should have clarified. The reserve tank will only fill the primary tank when the truck is off. So the EFI and low pressure transfer pump will never run simultaneously.

 

[theblindchicken]

Good point...

I guess I should have clarified. The reserve tank will only fill the primary tank when the truck is off. So the EFI and low pressure transfer pump will never run simultaneously.

No worries. Was just something that came to mind that could have posed an issue. Perhaps if you ran two separate lines, the vent for the primary tank would be enough to allow for enough of a pressure difference to allow for the 12v transfer pump to work at anytime?

 

[Frankenchevy]

No worries. Was just something that came to mind that could have posed an issue. Perhaps if you ran two separate lines, the vent for the primary tank would be enough to allow for enough of a pressure difference to allow for the 12v transfer pump to work at anytime?

I was worried about over filling the primary tank. I figured on only refilling the primary off the reserve when the primary was low and I’m between gas stations.

 

[theblindchicken]

I was worried about over filling the primary tank. I figured on only refilling the primary off the reserve when the primary was low and I’m between gas stations.

I'd bet you could add in a circuit that will auto activate the pump when the sender reaches a certain resistance, but that'd make it a bit more complicated. Would ensure that you would never accidentally run the primary tank dry unless you are 100% out of fuel in both tanks.

Cool idea for sure!

 

[hatzie]

Sniper is 60PSI??? If you use the 65PSI Pollack valve then you can plumb it using factory lines and electrical.

 

[Frankenchevy]

Sniper is 60PSI??? If you use the 65PSI Pollack valve then you can plumb it using factory lines and electrical.

The sniper has an integrated pressure regulator set at 58.5 psi.

I was trying to avoid the valve and two in tank pumps. The sniper triggers the pumps and needs a 2.5 second prime before operation. I wasn’t sure if switching tanks on the fly would be an issue. My other concern is ethanol compatibility with the valve and any other component in the system.

 

[foamypirate]

The sniper has an integrated pressure regulator set at 58.5 psi.

I was trying to avoid the valve and two in tank pumps. The sniper triggers the pumps and needs a 2.5 second prime before operation. I wasn’t sure if switching tanks on the fly would be an issue. My other concern is ethanol compatibility with the valve and any other component in the system.

I've been running a new Pollack valve and dual in-tank pumps on my LS swap (roughly the same 58psi requirement) for 2+ years, not a single problem, just as a data point. No issues with priming or swapping on the fly (other than the occasional momentary light stumble when switching).

 

[Frankenchevy]

Sniper is slightly different than oe efi on startup priming.

I couldn’t find any info on pollak valve being ethanol compatible. I want every piece to be e85 compatible. Hopefully they’ll ditch obama ethanol fuels in gasoline, but who knows...

My other option is tapping into the primary tank on the filler neck to transfer the fuel in.

 

[Splandman]

I just finished doing what you wanted to avoid. I have a Sniper and just had 87 tanks put in, 87 switch, and Walbro 255 pumps in each tank. It's working well now. I had an external frame mounted pump under the passenger tank. That did not work too well. I don't run e85, but ethanol free gas is easy to get where I live.

 

[hatzie]

The new ones are E15-E20 compatible. Not sure about E85 with the 42-159 valve. I submitted a question to Pollack technical about that. You may want to ask them for yourself. http://products.pollakaftermarket.c.../light-truck-6-port-motor-driven-valve/42-159

E85 is so hard to find most places I don't see it being an issue...

Can the Sniper change fuel maps for E85 on the fly? How well will it handle the partial tank that's not E85 and not E15 either? I've driven a Flex Fuel rental Suburban on E85 in Austin TX and the first partial tank was a little odd. I should've burned off a little more go-juice before filling up with E85.

The Flex Fuel engines have a lot more tech than just the electronics. I can't honestly recommend running Ethanol in an engine that was not built to handle it.

 

[Frankenchevy]

The new ones are E15-E20 compatible. Not sure about E85 with the 42-159 valve. I submitted a question to Pollack technical about that. You may want to ask them for yourself. http://products.pollakaftermarket.c.../light-truck-6-port-motor-driven-valve/42-159

E85 is so hard to find most places I don't see it being an issue...

Can the Sniper change fuel maps for E85 on the fly? How well will it handle the partial tank that's not E85 and not E15 either? I've driven a Flex Fuel rental Suburban on E85 in Austin TX and the first partial tank was a little odd. I should've burned off a little more go-juice before filling up with E85.

The Flex Fuel engines have a lot more tech than just the electronics. I can't honestly recommend running Ethanol in an engine that was not built to handle it.

While it can run e85, I’ll mostly be running e10. Even that stuff eats parts up.

 

[hatzie]

Those valves will handle E10 just fine. It was the E85, at eight and one half times that concentration, I questioned.

I would change all of the rubber lines to fresh SAE J30R9 hose, including the vapor lines, and use fresh SAE J30R10 submersible hose inside the tank. When the mandated sale of E10 fuels kicked in it forced a change in hose rubber formulations to meet the new fuel requirements. Anything that pre-dates that change is suspect at best and anything that doesn't have the SAE compliance number on the jacket isn't compliant.

 

[bluex]

Can the Sniper change fuel maps for E85 on the fly? How well will it handle the partial tank that's not E85 and not E15 either? I've driven a Flex Fuel rental Suburban on E85 in Austin TX and the first partial tank was a little odd. I should've burned off a little more go-juice before filling up with E85.

No it can't, it doesnt have a fuel sensor and I dont think its recommened to run on E85 as you would need to go in and manaully update the fuel tables to increase the amount delivered. There are some people running them on E85 but they are specifically tuned for that and that is the only fuel they run. It also lowers the HP levels it can support because you run out of injector pluse width/duty cycle faster.